No longer are sporting-goods makers relying just on the allure of a star athlete or a colorful design to sell athletic wear and equipment. As they build in technology to sell performance and safety advantages, they’re encountering the same sorts of legal challenges to their features as makers of smartphones and medical devices have.

Patent-infringement lawsuits were filed this year against Beaverton, Ore.-based Nike over its FuelBand monitor, through which users download heart rates and other data to a smartphone application, and its Hyperdunk+ and LeBron X+ shoes, the latter named for the Miami Heat’s LeBron James.

The litigation promises to be expensive — patent cases with more than $25 million at stake cost $5 million on average, according to the American Intellectual Property Law Association — and could determine winners in the growing market.

“You have a relatively small industry, with a relatively few number of players and incredibly competitive companies,” attorney Brian Rosenthal of Mayer Brown in Washington. “Everytime there’s a technological advance, everyone wants to be number one.”

Gadgets that combine electronics with athletic equipment are the fastest growing segment of the so-called wearable device market, which also includes Google’s Google Glasses, according to Juniper Research, based in Hampshire, England. The market is projected to grow from about $800 million this year to $1.5 billion in 2014, said Nitin Bhas, a researcher with Juniper in London.

Nike isn’t the only sporting-goods maker sued over its innovations, and the sector could be the next big patent battleground after the smartphone litigation tying up Apple, Google’s Motorola unit, Samsung Electronics and other technology companies.

SportBrain Inc., an Austin, Texas-based company that sells pedometers, sued Herzogenaurach, Germany-based Adidas and Fitbit Inc. over their activity monitors.

Easton-Bell Sports Inc.’s Riddell unit, the official maker of helmets for the National Football League, is accused of infringing a Colorado company’s patents for headgear that measures the impact of a tackle or other blow and transmits it to a wireless device.

The NFL, which is facing lawsuits from more than 4,000 former players, and Riddell are under pressure to provide more protection from repeated head blows that have been linked to a progressive brain disease that can lead to dementia and death.

Electronics companies including Samsung and Royal Philips are also obtaining fitness patents, said David Cornwell, a lawyer with Sterne Kessler in Washington whose clients include Adidas. “I’m seeing a lot of companies that I wouldn’t expect for sports electronics,” Cornwell said.

The smartphones have applications to let a user easily measure progress and get feedback, while a computer chip known as a micro-electro mechanical system, or MEMS, tracks movement or speed more accurately through motion sensors.

Fitbug Holdings Chief Executive Officer Paul Landau recalls being “in quite a lonely space” in 2005 when his London-based company started selling its electronic devices that monitor fitness activity and track progress online.

Landau said in an interview he “was having to do all the evangelizing, that you could use devices that could upload data and you could use online tools to motivate and achieve goals.”

Companies envision a day when, for instance, one coach will be watching players on the field while another is keeping tabs on their vital signs on a tablet computer.

Nike is relying on its innovations to develop brand loyalty and drive sales. In the past year, it’s obtained patents on golf clubs that analyze one’s swing, and a computerized soccer ball to evaluate the strength of a kick.

Mary Remuzzi, a Nike spokeswoman, declined to comment on the patent litigation. Among the patents Adidas was awarded recently was one for “intelligent footwear systems” — sneakers with sensors that can adjust the cushion or sole based on how the shoe is being used.

‘’We are talking about technology that is real, not a pipe dream,’’ said former NFL player Isaiah Kacyvenski, now director of sports business at Cambridge, Massachusetts-based MC10 Inc., which is developing flexible sensors that can be put on the body to monitor heart rate or other vital signs.

A decade-long patent battle between Titleist Pro V maker Acushnet Co., now owned by a group led by Fila Korea Ltd., and Callaway Golf Co. was only settled last year, said Rosenthal, who represented Acushnet in the fight.

‘’It’s fair to expect that as technology plays a more important role in differentiating athletic companies, a natural part of that — as with any other industry — is for there to be an expansion of patent litigation,’’ said Matt Gaudet, a patent lawyer with Duane Morris in Atlanta.

For now, most of the new innovations are for the dedicated athlete or fitness buff. Nike’s top technology, called Elite+, can add $100 to the price of a LeBron James shoe that already costs $160, said Matt Powell, analyst with Boulder, Colorado- based SportsOneSource.

‘’Our phones do far more than we ask them to do,’’ Powell said. ‘’Why shouldn’t our shoes do more, too?’’

— With assistance from Matt Townsend, Aaron Kuriloff and Mason Levinson in New York